Radar systems are vital to the operations of various agencies such as the National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS), the Federal Aviation Administration (FAA), the Department of Defense (DOD) and the Department of Homeland Security (DHS). These agencies have multiple requirements for modern radar technology covering a wide range of operational purposes including weather observation, meteorological research, aircraft tracking, unmanned aircraft systems surveillance and surface transportation.
As each of these agencies requires a radar system with unique capabilities, the current radar infrastructure comprises a wide variety of radar types and configurations. For example, weather tracking operations by the NOAA and FAA may require a system capable of dual-polarization operation. However, radar tasks associated with the DHS and/or other FAA operations do not have such requirements. Likewise, a narrow beamwidth, for example, no greater than one (1) degree, may be required for certain tracking operations but not for others. These parameters may necessitate variations in antenna array size, radiating element type, cost, and/or complexity.
As many existing radar systems are coming due for replacement, government and industry are working to transition from these individualized systems to a universal system capable of meeting the various agency demands, while offering reduced complexity and substantial cost savings. One proposed solution is digital phased array technology, specifically multi-function phased array radar (MPAR). A phased array antenna is comprised of numerous radiating elements each having a phase shifter. Beams are formed by selectively activating all or a portion of antenna elements of a given array. The beam pattern of these antennas can be controlled to produce one or more directed beams, which may be broad or narrow (“pencil” type). Scanning or steering of the beams is accomplished by shifting the phase of the signals emitted from the elements in order to provide constructive and/or destructive interference. The ability to form and steer a radar beam permits multiple functions to be performed by the same radar system. In addition to multi-function operation, these arrays have a quicker response time and operate at a higher resolution than existing rotating radar systems.
While MPAR offers advantages over current arrangements, several technical and economic obstacles need to be overcome before it can be implemented successfully as a universal system. One such example of an application creating technical challenges is the above-described weather-related radar systems.
For example, a current requirement for the next-generation weather system is to provide one (1) degree of angular resolution. However, it has been shown that some meteorological signatures, such as mesocyclone and tornado vortex signatures, can be detected at greater ranges using radar data with finer resolution, more particularly, an angular resolution of one-half (0.5) of one degree. Radar data produced at this angular resolution is termed “super-resolution” data. As this enhanced resolution increases the range at which small tornado parent circulation patterns can be detected, weather tracking systems using super-resolution data may provide more advanced warnings. Super-resolution data also provides additional detail to aid in other severe storm analysis and weather-related risks, such as predicting flash floods.
Current solutions capable of achieving super-resolution data may utilize over-sized antenna arrays in order to generate a very narrow beam width, and thus a higher angular resolution. However, this increased antenna array size is impractical for use in a universal application and is not cost effective. Other solutions include the use of exceedingly costly antenna elements having improved angular resolution. These elements are cost-prohibitive for use in a universal system.
Accordingly, alternate methods of achieving sufficiently narrow angular resolution, in particular super-resolution, in an MBAR system are desired.